The invention is directed to a turnover device for turning a web-shaped recording medium over. The invention is particularly advantageous arranged between two electrographic printer or copier devices working in tandem mode.
Such a turnover device is disclosed, for example, by WO 92/15513. It serves the purpose of turning the paper web over between two printer devices operating in tandem mode in order, for example, to thus enable duplex printing.
What is disadvantageous about the known turnover device is its broad structure and the offsetting of the paper web that prevents an aligned arrangement of the two printers participating in the printing.
An aligning arrangement of the printers, however, is beneficial when the printers are also used without a turnover device for printing a paper web on one side, for example with two superimposed images. In order to avoid imprecisions in the paper running, a straight: line guidance with a paper web between the printers is necessary in this operating mode. When papers webs of different widths are employed, one side edge serves as a firmly prescribed reference edge in the paper channel. In this case, too, it is necessary to align the printers according to this reference edge. Realigning the printers every time dependent on the operating mode is complicated and time-consuming and is hardly possible given electrographic high-performance printers that are permanently installed.
When web-shaped materials are deflected with drums, rollers or rods residing obliquely relative to the conveying direction, the diameters or, respectively, cross sections of these deflector parts also enter into the lay of the web position. This effect especially gains significance when the recording medium is deflected by a plurality of such deflector parts as, for example, given the crossed turners having two crossed turnover elements and a lateral deflector element as disclosed by U.S. Pat. No. 3,206,089. When the web guidance is defined, for example, in tandem printing at the input and output side of the printers and cannot be modified due to the employment of a turnover device, the position of the material web should be independent of the influence of the turnover device.